Conventionally, as illustrated in FIG. 20, there is known sensible heat exchanger 11 that includes two flow paths A and B (respectively indicated by the solid and dashed arrows). Sensible heat exchanger 11 can move heat from one flow path A to the other flow path B when warm air flows through one flow path A and cold air flows through the other flow path B.
The heat exchanger is installed in a vehicle air-conditioning apparatus, for example, and is used to replace air inside a vehicle interior (referred to as internal air) and air outside a vehicle (referred to as external air) without discharging the heat inside the vehicle interior to the outside of the vehicle when the inside of the vehicle interior is ventilated (for example, see PTL 1).
In the vehicle air-conditioning apparatus of the related art, the flow path A and flow path B are fixedly used to let external air and internal air to pass through the flow path A and flow path B, respectively.